Information recording and reproducing apparatus

Abstract: An information recording and reproducing apparatus is disclosed which prevents the bearing surface of an auxiliary bearing (23) of a card carriage (6) in sliding contact with an auxiliary guide rail (5) from being locally worn. A main guide rail (4) and the auxiliary guide rail (5) are spaced in the same plane. The axis of the auxiliary guide rail (5) is oblique at a predetermined very small angle to the axis of the main guide rail (4). The auxiliary bearing (23) has a bearing bore having a slot-shaped cross section. Portions of the bearing surface of the bearing bore which are in contact with the auxiliary guide rail (5) are displaced transversely to the direction of the stroke of the card carriage (6) during the stroke.

Description: The present invention relates to an information recording and reproducing apparatus comprising a chassis, a main guide rail and an auxiliary guide rail spaced on an upper surface of the chassis, the main guide rail and the auxiliary guide rail respectively having circular cross sections and the axis of the auxiliary guide rail being positioned in the same plane as the axis of the main guide rail, a card carriage capable of retaining an optical memory card, the card carriage being slidably mounted by means of main and auxiliary bearings on the main and auxiliary guide rails and linearly movable along the main and auxiliary guide rails, the main guide bearing having a round cylindrical bearing surface fitting the cylindrical surface of the main guide rail and the auxiliary plain bearing having a bearing opening with a slot-shaped cross section, the opposite upper and lower surfaces of the bearing opening of the auxiliary bearing being in contact with the cylindrical surface of the auxiliary guide rail, a head carriage movable perpendicularly to the direction of movement of the card carriage, and an optical recording and reproducing head, fixedly mounted on the head carriage, for recording and reproducing data into and out of the optical memory card. Such an apparatus has been known from EP-A-0508111. In this apparatus the opening of the auxiliary plane bearing has a U-shaped form, whereas the guide rails are parallel. This prior art information recording and reproducing apparatus has the following drawback: While the main plain bearing is sufficiently durable for a longtime service, since the main plain bearing has a round cylindrical bearing surface which is in sliding contact with the main guide rail, the auxiliary plain bearing is in line contact with a certain portion of the auxiliary guide rail. Therefore, a wearing due to this line contact tends to proceed in the operation of the apparatus, so that the auxiliary plain bearing has a poor durability. The wearing makes it difficult to maintain the level of the upper surface of the card carriage at an initial level, so that a predetermined distance for recording and reproducing data between the optical recording and reproducing head and the optical memory card cannot be accurately maintained. Since the card carriage experiences an oscillation due to the wearing at a certain position in the bearing surface of the auxiliary plain bearing, the card carriage does not stably reciprocate. This adversely affects a recording and a reproduction of the information on and from the optical memory card. In the prior art information recording and reproducing apparatus known from DE-A-3837067 the bearing surface for the main guide rail is cylindrical, whereas the bearing surface for the auxiliary guide rail is elliptic. Also in this apparatus the guide rails are parallel. The object of the present invention is to provide an information recording and reproducing apparatus of the type defined in the preamble of claim 1, which prevents a portion of an auxiliary plain bearing of a card carriage in contact with an auxiliary guide rail from being locally worn to preclude an oscillation due to the local wearing and stably move the card carriage forward and rearward for a long time. In order to achieve this object, in the information recording and reproducing apparatus according to the invention the axis of the auxiliary guide rail is oblique at a predetermined very small angle into a predetermined direction to the axis of the main guide rail. The auxiliary bearing may have a U-shaped bearing surface, the opposite portions of which are in contact with the cylindrical surface of the auxiliary guide rail. In the operation of this apparatus, since the auxiliary guide rail is oblique at a predetermined very small angle to the main guide rail, contact portions of the bearing surfaces of the auxiliary bearing are displaced transversely from the axis of the main guide rail during the stroke of the card carriage. This displacement prevents the bearing surfaces of the auxiliary bearing from being locally linearly worn to suppress an oscillation of the card carriage during the forward and rearward strokes of the card carriage and enable stable forward and rearward strokes of the card carriage. FIG. 1 is a perspective view of an information recording and reproducing apparatus according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line A-A in FIG. 1, showing a card retention state of card retainers of the information recording and reproducing apparatus of FIG. 1. FIG. 3 is a plan view of a card carriage in a front stop position. FIG. 4 is a sectional view taken along the line D-D in FIG. 3. FIG. 5 is a plan view of a card carriage in a rearmost stop position. FIG. 6 is a sectional view taken along the line F-F in the FIG. 5. FIG. 1 is a perspective view of an information recording and reproducing apparatus according to an embodiment of the present invention. A rectangular chassis is indicated at 1. Four corners of the chassis 1 have upright brackets 2a, 2b, 3a and 3b mounted thereon. A main guide rail 4 has a circular cross section and horizontally extends between the brackets 2a and 2b. An auxiliary guide rail 5 has a circular cross section and horizontally extends between the brackets 3a and 3b. The guide rails 4 and 5 are positioned so that the axes of them lie in the same horizontal plane and so that the axis of the auxiliary guide rail 5 is oblique at a predetermined very small angle  to the axis of the main guide rail 4. Thus, the main guide rail 4 and the auxiliary guide rail 5 are not parallel to each other and extensions thereof intersect each other at a certain point. A card carriage 6 in the form of a rectangular board is mounted longitudinally slidably to the main guide rail 4 and the auxiliary guide rail 5. As seen in FIG. 4, a linear motor 7 moves the card carriage 6 between a front stop position and a rearmost stop position. An upper surface of the card carriage 6 retains a rectangular optical memory card 8 in a predetermined position. As shown in FIG. 1, the optical memory card 8 includes a rectangular data storage region 9a as a central region extending along the longitudinal axis thereof and data-free or guard regions 9b adjoining the opposite longitudinal peripheries of the data storage region 9a. A front mask unit 10 is mounted by means of a bracket (not shown) on the upper surface of a stepped-down floor extending forward from the front end of the chassis 1. The front mask unit 10 has a card passage 11 extending through it along the anterior-posterior axis of it. The front end of the card passage 11 has a card receiving slot 12. The rear end of the card passage 11 has a card discharging slot 13. The optical memory card 8 is inserted into the card receiving slot 12, let out through the card discharging slot 13 and transferred to the upper surface of the card carriage 6. The front mask unit 10 has a slot 14 extending along the anterior-posterior axis thereof. A feed roller set which pinches the optical memory card 8 and delivers it to the upper surface of the card carriage 6 is mounted in the slot 14. The feed roller set comprises a pair of drive rollers 16 driven by an electrical motor and belt assembly (not shown), and follower rollers 17 mating the drive rollers 16. The drive rollers 16 and the follower rollers 17 serve as pinch rollers pinching the optical memory card 8. Once an operator has inserted the optical memory card 8 into the card passage 11 to a predetermined depth, a card sensor (not shown) provided in the card receiving slot 12 senses the optical memory card 8 and produces a signal for moving the electrical motor. Thus, the electrical motor rotates the drive rollers 16 and in turn the feed roller set delivers the optical memory card 8 to the upper surface of the card carriage 6 through the card discharging slot 13. Above the card carriage 6, an optical recording and reproducing head 18 is supported on a head carriage frame (not shown). A linear motor (not shown) moves the optical head 18 up and down perpendicularly to the travel direction of the card carriage 6. The optical head 18 includes a laser source 19. The laser source 19 transmits a laser beam for writing and reading data to the data storage region 9a in the optical memory card 8. As shown in FIGS. 1 and 2, a main-guide-rail-side edge of the card carriage 6 has two main plain bearings 21 and 22. Each of the main plain bearings 21 and 22 has a round cylindrical bearing bore and is in sliding contact with the main guide rail 4. On the other hand, an auxiliary-guide-rail-side edge of the card carriage 6 has an auxiliary plain bearing 23. The auxiliary plain bearing 23 has a bearing opening having a generally elliptic cross section and is in contact with the auxiliary guide rail 5. The bearing opening of the auxiliary plain bearing 23 includes flat upper and lower surfaces in contact with the auxiliary guide rail 5. The card carriage 6 is movable forward and rearward along the main and auxiliary guide rails 4 and 5 so that the main plain bearings 21 and 22 are in sliding contact with the main guide rail 4 and the auxiliary plain bearing 23 is in sliding contact with the auxiliary guide rail 5. The main guide rail 4 has two stop bushings 24 and 25 mounted thereon. The front stop position of the card carriage 6 is defined as a position in which the position of the card carriage 6 is nearest to the card discharging slot 13 of the front mask unit 10 in the stroke of the card carriage 6. The front edge surface of the main plain bearing 21 contacts the front stop bushing 24 to delimit the forward stroke of the card carriage 6. On the other hand, the rearmost stop position of the card carriage 6 is defined as a position in which the position of the card carriage 6 is remotest from the card discharging slot 13 in the stroke of the card carriage 6. The rear edge surface of the main plain bearing 22 contacts the rearmost stop bushing 25 to delimit the rearward stroke of the card carriage 6. Thus, the card carriage 6 reciprocates between the front and rearmost stop positions. The main-guide-rail-side edge of the card carriage 6 has a rigid card retainer plate 26. The auxiliary-guide-rail-side edge of the card carriage 6 has a flexible card retainer plate 27. The card retainer plates 26 and 27 can retain the optical memory card 8 on the upper surface of the card carriage 6. In operation, contact portions of the upper and lower bearing surfaces of the auxiliary plain bearing 23 are displaced transversely from the axis of the main guide rail 4 during the stroke of the card carriage 6 between the front and rearmost stop positions. FIGS. 3 and 4 show the card carriage 6 in the front stop position. FIGS. 5 and 6 show the card carriage 6 in the rearmost stop position. As shown especially in FIGS. 4 and 6, the contact portions of the upper and lower bearing surfaces of the auxiliary plain bearing 23 are displaced transversely to the direction of the stroke of the card carriage 6. Thus, the lengths of the upper and lower bearing surfaces of the auxiliary plain bearing 23 must cover at least a transverse displacement of cos(90°-) during the stroke of the card carriage 6 with the auxiliary plain guide rail 5 oblique at a very small angle  to the main plain guide rail 4. The shape of the cross section of the bearing opening of the auxiliary plain bearing 23 is not restricted to a generally ellipsis having upper and lower flat sides but may be, e.g., a U-shape having upper and lower flat sides. Since the open ends of the cross section of such U-shaped auxiliary plain bearing may gradually increase during a longtime service, the auxiliary plain bearing having a bearing opening with such elliptic cross section can ensure more stable forward and rearward strokes of the card carriage 6.

Claims: An information recording and reproducing apparatus comprising a chassis (1), a main guide rail (4) and an auxiliary guide rail (5) spaced on an upper surface of the chassis (1), the main guide rail (5) and the auxiliary guide rail (4) respectively having circular cross sections and the axis of the auxiliary guide rail (5) being positioned in the same plane as the axis of the main guide rail (4), a card carriage (6) capable of retaining an optical memory card (8), the card carriage (6) being slidably mounted by means of main and auxiliary bearings (21, 22; 23) on the main and auxiliary guide rails (4, 5) and linearly movable along the main and auxiliary guide rails (4, 5), the main guide bearing (21, 22) having a round cylindrical bearing surface fitting the cylindrical surface of the main guide rail (4) and the auxiliary plain bearing (23) having a bearing opening with a slot-shaped cross section, the opposite upper and lower surfaces of the bearing opening of the auxiliary bearing (23) being in contact with the cylindrical surface of the auxiliary guide rail (5), a head carriage movable perpendicularly to the direction of movement of the card carriage (6), and an optical recording and reproducing head (18), fixedly mounted on the head carriage, for recording and reproducing data into and out of the optical memory card (8), characterized in that the axis of the auxiliary guide rail (5) is oblique at a predetermined very small angle () to the axis of the main guide rail (4) in order that contact portions of the upper and lower surfaces of the auxiliary bearing opening (23) with the auxiliary guide rail (5) are displaced transversely from the axis of the main guide rail (4) during the linear movement of the card carriage (6). The apparatus as recited in claim 1, characterized in that the auxiliary bearing (23) has a U-shaped bearing surface, the opposite portions of which are in contact with the cylindrical surface of the auxiliary guide rail (5). n

Inventors: HAYASHI HIROSHI, MATSUO MINORU, OGINO TADAO, HAYASHI, HIROSHI, MATSUO, MINORU, OGINO, TADAO
Applicants: NIPPON CONLUX CO LTD, NIPPON CONLUX CO., LTD.
Application year: 1994
Main classification: G11B25
IPC codes: G06K13, G11B25, G11B17